Understanding the basic genetic and molecular markers of cancer at the cellular level is vital for preventing, diagnosing, and treating cancer. Recent work in our lab has led to new technologies for manipulating small aqueous drops containing biological molecules. We use laser light to induce surface tension gradients, which allows us to selectively move very small individual droplets (mu L-pL), and we have performed simple enzymatic assays with this approach. Because our technique uses laser heating as a basis for droplet control, we believe that it is well suited to genomic analysis methods, such as polymerase chain reaction (PCR), which rely on thermal cycling. We propose to combine our laser-based droplet control techniques with genomic analysis tools to develop a device for screening large numbers of individual cells. To test the capabilities of our apparatus, we propose an R21 project with the following specific aims: Aim 1: Optimize and automate the liquid handling system for genomic analysis. We will choose the optimal materials and reagents for use in our apparatus. We will automate both the droplet delivery and the droplet handling capabilities of our device. Aim 2: Perform a real-time PCR in our droplet-based system. We will test the overall sensitivity and quantify nonspecific amplification in our binary liquid system. Aim 3: Examine single cells within small droplets. This examination will include testing for short- and long-term cell viability and PCR amplification of single-cell genomic material. This research is fully consistent with the goals outlined in RFA-CA-06-002. If this program is successful, we believe that the resulting technology will prove invaluable in helping doctors and scientists better understand the molecular basis of cancer while also providing tools to help diagnose specific variants of disease, plan and assess therapy, and monitor disease recurrence. [unreadable] [unreadable] [unreadable] [unreadable] [unreadable] [unreadable] [unreadable]